The present invention relates to methods for manufacturing semiconductor devices, and methods and structures for implementing the semiconductor devices.
Conventionally, Chip On Glass (COG) connection is known as a connection method used for implementing a driver IC on a substrate of a display device. In the COG connection, for example, an Au plating bump (hereinafter, a “bump”) is formed in the driver IC as an electrode. Then, using a conductive joint material such as an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP), the bump is electrically connected with a terminal electrode formed on the substrate of the display device. The driver IC is thus implemented on the substrate.
However, recently, smaller-sized electrodes are often employed (smaller-pitched arrangement of electrode is often used). The pitch between the electrodes thus becomes substantially equal to the size of a conductive particle contained in the ACF. Accordingly, the conductive particle may interfere with the electrodes, causing a short circuit.
So as to avoid the problem, a joint material free from conductive particles (for example, a non-conductive paste (NCP)) may be used for implementing the driver IC on the substrate. However, this hampers contact between the bump of the driver IC and the terminal electrode on the substrate. Such failure of contact decreases the reliability of connection between the driver IC and the terminal electrode.
In order to maintain the connection reliability, a projection electrode (Japanese Laid-Open Patent Publication No. 64-13734 (=No. 1-13734)) may be used. More specifically, the projection electrode has a projection formed of resin and wiring provided in the projection. The traces of wiring extend from an electrode formed in the driver IC. The projection electrode contacts the terminal electrode formed on the substrate. In this state, a distal portion of the projection electrode is pressed against the terminal electrode and thus deformed. This increases the contact area between the projection electrode and the terminal electrode, maintaining stable communication between the projection electrode of the driver IC and the terminal electrode of the substrate. Accordingly, regardless of the use of the joint material free from the conductive particles, the reliability of the communication between the bump of the driver IC and the terminal electrode of the substrate is maintained.
To form the projection electrode, the projection is shaped by curing photosensitive insulating resin, or the material of the projection, through exposure to, for example, ultraviolet rays. However, in this case, as a lamp for exposure deteriorates, the condition for exposure may change. This makes it difficult to shape the projection, decreasing productivity of the semiconductor device.
Further, if a core portion of the projection electrode is formed of a resin with relatively low elasticity such as silicone, the resin may deform excessively under certain conditions when pressed for implementation. This may cause a break of the traces of the projection electrode, thus decreasing the reliability of connection between the projection electrode of the driver IC and the terminal electrode of the substrate. In addition, in order to improve the productivity, the joint material may be formed of a material that is cured in a relatively short curing time if the curing temperature is raised. It is thus necessary to configure the projection electrode in such a manner that the connection between the projection electrode and the terminal electrode is reliably maintained when heated in implementing of the IC driver on the substrate.